.45 ACP
'' The .45 ACP'' (11.43×23mm, ACP meaning Automatic Colt Pistol), also known as the .45 Auto ''by C.I.P. or ''45 Auto by SAAMI, is a cartridge designed by John Browning in 1904, for use in his prototype Colt semi-automatic .45 pistol and eventually the M1911 pistol adopted by the United States Army in 1911. It was used in the Springfield XD-45 Tactical pistol in White House Down. Description The .45 ACP boasts devastating and powerful ballistics since the cartridge was designed to fire a heavy, large lead bullet at a target with much force, perfect for combat or police use. In fact, .45 ACP was the official pistol cartridge for the US Military from 1911 to 1985. The .45 ACP is an effective combat pistol cartridge that combines accuracy and stopping power for use against human targets. The cartridge also has relatively low muzzle blast and flash, as well as moderate recoil. The .45 ACP also operates at a relatively low maximum chamber pressure rating of 21,000 psi (145 MPa) (compared to 35,000 psi/240 MPa for 9mm Parabellum and .40 S&W, 37,500 psi/260 MPa for 10mm Auto, 40,000 psi/280 MPa for .357 SIG), which due to a low bolt thrust helps extend service life of weapons in which it is fired. Like many pistol cartridges, it is a low-velocity round, and thus ineffective against body armor. Another drawback for large scale military operations is the cartridge's large size, weight, and the increased material cost of manufacture compared to the smaller 9×19mm Parabellum cartridge. Even in its non-expanding full metal jacket (FMJ) version, the .45 ACP cartridge has a reputation for effectiveness against human targets because its large diameter creates a deep and substantial permanent wound channel which lowers blood pressure more rapidly. The wounding potential of bullets is often characterized in terms of a bullet's expanded diameter, penetration depth, and energy. Bullet energy for .45 ACP loads varies from roughly 350 to 500 ft·lbf (470 to 680 J). ATOMIC Ammunition produces a new load that pushes a 185 grain copper bonded hollow point bullet to 1225 feet per second and achieves over 616 foot pounds of energy. This load safely conforms to SAAMI specifications for 45 ACP+P and outperforms certain 10mm and 357 Magnum loads by other manufacturers. The table below shows common performance parameters for several .45 ACP loads. Bullet weights ranging from 185 to 230 grains are common. Penetration depths from 11 inches to over 27 inches are available for various applications and risk assessments. The .45 ACP's combination of stopping power and controlled penetration makes it practical for police use, although numerous issues, including the resulting decrease in magazine capacity and the larger size and weight of pistols chambered in this caliber, have led more police departments in the USA to adopt sidearms in 9×19mm, .40 S&W, and .357 SIG. With standard (not extended) single-stack magazines, pistols chambered in .45 ACP usually hold 8 rounds or less (exceptions to this include the 9-round .45 ACP versions of the Smith & Wesson SW99 and the Beretta Px4 Storm). However, many modern versions of .45 ACP handguns have double-stack magazines capable of holding as many as 14 rounds, such as the .45 ACP versions of the FN FNP and FN FNX, though this greatly increases the pistol's bulk and with that lowers maneuverability. The Glock 21 can only hold 13 rounds of .45 unless it has an extended magazine and the FNP boasts the highest known .45 capacity on the market, at 15 rounds. Some speculate that the FNP will replace the Beretta M9 as the US Military sidearm, returning .45 to the armed forces once again. Many US tactical police units still use the .45 pistol round, including the FBI's Hostage Rescue Team. While high capacity firearms are available in .45 ACP, the greater length and diameter of the .45 ACP means that the grip of the pistol must be longer and wider than the grip of a comparable pistol of a smaller caliber; this increase in grip size can make the pistol difficult to use for shooters with smaller hands. Today, most NATO militaries use sidearms chambered for the 9×19mm Parabellum cartridge, but the effectiveness of the .45 ACP cartridge has ensured its continued popularity with large caliber sport shooters, especially in the United States. In addition, select military and police units around the world still use firearms firing the .45 ACP. In 1985, the .45 ACP M1911A1 pistol was replaced by the Beretta M9 9mm pistol as the main sidearm of the U.S. military, although select Special Operations units continue to use the M1911A1 or other .45 ACP pistols. Because standard pressure and load .45 ACP rounds fired from handguns or short barreled submachine guns are inherently subsonic, it is one of the most powerful pistol calibers available for use in suppressed weapons since subsonic rounds are quieter than supersonic rounds. The latter inevitably produce a highly compressed shock wave, audible as a loud "crack", literally a small sonic boom, while they travel through the air. Suppressors reduce the audible "report" by slowing and channeling the high speed gas generated by the burning/expanding gunpowder before it exits the muzzle resulting in a muffled "cough". Suppressors cannot act on a supersonic shock wave continuously generated by a bullet exceeding the 1,087 ft/s (331 m/s) speed of sound at 32 °F (0 °C) ambient cold temperatures, as this shock wave is continuously produced throughout the entire flight path over which the bullet is supersonic, which extends long after it exits the barrel. The downside to the use of .45 ACP in suppressed weapons is that increasing the diameter of the passage through a suppressor decreases the suppressor's efficiency; thus, while .45 ACP is among the most powerful suppressed pistol rounds, it is also one of the loudest. Most .45 suppressors must be fired "wet" (with an ablative medium, usually water) to bring sound levels down to "hearing-safe" (under 140 dB, generally). Category:Cartridge Category:Weapons